Intermittent linear motor

Abstract

The intermittent linear motor of this invention incorporates features which enhance the exhaust scavenging and cooling processes, as well as simplifying overall construction including a compression plenum below the piston where air displaced during a power stroke by the piston is immediately transferred through the combustion chamber allowing said compressed air to immediately begin scavenging exhaust gases as the piston is returned by a resilient member further displacing spent gases from the motor.

I claim:  
     
       1. In a combustion gas powered intermittent linear motor having a combustion chamber, an associated piston reciprocating in a piston chamber, the piston powered in a power stroke by ignition of gas in the combustion chamber and biased to return to rest in a return stroke, when not powered by the ignition of gas, an exhaust valve associated with the combustion chamber, which valve opens to exhaust spent combustion gases and air from the combustion chamber after combustion, the improvement characterized in that a plenum chamber is provided, this plenum chamber being in fluid communication with the piston chamber below the piston remote from the combustion chamber, the plenum chamber further being in further communication with a combustion chamber, the motor configured so that: 
       a. air is compressed in the piston chamber below the piston during the power stroke and this compressed air is compressed into the plenum chamber;  
       b. then, as the combustion chamber pressure drops, the compressed air from the plenum chamber flows through the combustion chamber, and subsequently through the exhaust valve, scavenging the combustion chamber of spent combustion gases;  
       c. as the plenum chamber pressure drops and the piston is on its return stroke, the piston draws in air from below it through an air inlet means in the piston chamber while exhaust gases above the piston are being forced out through the exhaust valve;  
       d. as the pressure in the combustion chamber and the plenum chamber return to substantially atmospheric pressure, said exhaust valve closes to ready the motor for fuel injection and ignition; and  
       e. an air bypass vent associated with the piston chamber is arranged so as to allow air compressed in the piston chamber below the piston during the power stroke to enter the piston chamber above the piston as the piston reaches the bottom of its power stroke, thereby assisting in the scavenging of the combustion chamber of spent combustion gases and in cooling the combustion chamber during the scavenging process.  
     
     
       2. A motor according to  claim 1 , wherein the communication between the plenum chamber and the piston chamber is controlled by a normally closed plenum check valve, that check valve being in opened position to allow air compressed below the piston during the power stroke into the plenum chamber. 
     
     
       3. A motor according to  claim 1 , wherein the plenum is also in fluid communication with a normally closed exhaust valve actuator for the combustion chamber exhaust valve. 
     
     
       4. A motor according to  claim 3 , wherein compressed air from the plenum chamber is fed to the exhaust valve actuator to bias the exhaust to open as the pressure in the combustion chamber begins to decrease at or near the end of the power stroke. 
     
     
       5. A motor according to  claim 3 , wherein the fluid communication between the plenum and the exhaust valve actuator is through a check valve/orifice means which is arranged so that the exhaust valve opens quickly but closes slowly, whereby the plenum chamber can drop to substantially atmospheric pressure before the exhaust valve closes. 
     
     
       6. A motor according to  claim 1 , wherein the swept volume of the piston is equal to or greater than two times the volume of the combustion chamber. 
     
     
       7. A motor according to  claim 1 , wherein the exhaust valve is spring biased to its closed position. 
     
     
       8. A motor according to  claim 1 , wherein the combustion chamber check valve is spring biased to its closed position. 
     
     
       9. A motor according to  claim 1 , wherein the exhaust valve is mechanically opened by a fluid driven piston actuator or diaphragm. 
     
     
       10. A motor according to  claim 3 , wherein the plenum is in fluid communication with a piston or diaphragm operated valve actuator for the combustion chamber exhaust valve. 
     
     
       11. A motor according to  claim 1 , wherein the combustion chamber is in fluid communication with a normally closed exhaust valve actuator and arranged so that the compression chamber pressure biases the exhaust valve actuator to open the exhaust valve at or near the end of a power stroke as the pressure in the combustion chamber decreases. 
     
     
       12. A motor according to  claim 1 , wherein the air inlet means is in the form of a check valve. 
     
     
       13. A motor according to  claim 1  wherein a portion of the air compressed in the piston chamber below the piston adds to an initial returning force applied to the piston on its return stroke.